Peristalsis is a series of wave-like muscle contractions that occur in the digestive tract, facilitating the movement of food through the esophagus, stomach, and intestines. These rhythmic contractions help push the contents along the digestive system, allowing for proper digestion and absorption of nutrients. Peristalsis is an involuntary process, controlled by the autonomic nervous system, and plays a crucial role in maintaining gastrointestinal motility.